How does population density affects housing in Japan?

Because flat land in japan is so limited housing is so expensive and there much smaller than usual that's why

most families own apartments rather than houses those apartments are no bigger than a regular family room in a American household they also have multipurpose rooms and may also own smaller appliances for there kitchen and some family members will own futons and sleep in the floor rather then in a bed and many apartments are own by nuclear families and extended families have begun to shrink

This might be a typical dining table for a
Japanese couple it can be easily stored
in a multipurpose room